There are in the art various types of disc prosthesis designed to enable one or more of the movements of flexion-extension, lateral bending and rotation between two adjacent vertebrae.
All of them have the drawback that they facilitate movement within excessive limits. Indeed, constructive solutions for disc prosthesis aim to ensure that movements, mainly flexion and extension, lateral bending and rotation, can be easily and smoothly made but at the same time they do not avoid the significant problems that can occur when anyone of these movements exceeds the physiological limits of the spine of each person.
Therefore, although getting a patient to regain normal range of motion of the spine is a major achievement, it is a potential danger that flexion-extension, lateral flexion or rotation exceed limits which may seriously impair the structures adjacent to the vertebral bodies causing, for example, degeneration of the facet joints, or may even affect the integrity of the spinal cord or, more commonly, that of the nerve roots that come out of it.
Therefore, there is a need to provide a disc prosthesis that avoids the drawbacks mentioned above by ensuring that the movements provided by the prosthesis have essentially the same limits as the patient's physiological limits.
One such disc prosthesis is claimed in appended claim 1.